How is continental crust formed?

Scientists have long believed that continental crust forms in volcanic arcs—they know the magma brought up in the arcs' volcanoes is geochemically very similar to continental crust. ... These old arcs formed, crashed into North America, turned on their sides, and were eroded over millions of years. read more

Oceanic crust is mostly composed of minerals that are low in silica (Olivine, Pyroxene, Amphibole), while continental crust is mostly composed of minerals that a high in silica (Quartz, Feldspar). There are many variations and the rocks form a spectrum of composition, but for the sake of simplicity we will stick with this separation. read more

The lingering question has been how exactly that happens. While the magma that reaches the surface is similar to continental crust, the lower crust beneath volcanic arcs is quite different from the lower half of continental crust. read more